Certain bacteria contain genes that encode proteins and/or enzymes, which degrade or confer resistance to toxic compounds. Bioluminescent reporter plasmids will be constructed from these genes (containing their promoter elements) by linkage to other genes with the capability of light emission (bacterial luciferase genes). These plasmids will be introduces into suitable host bacteria in order to produce a biological detection system, capable of detecting low concentrations of Superfund hazardous substances such as chromium (VI), arsenic (arsenate and arsenite), and nickel. The recombinant bacteria will be examined for expression of the resistance genes and the luciferase genes in the presence of the hazardous substances. Specifically, when the targeted hazardous substance is present in the sample, production of resistance-related proteins from the genes in the constructed reported plasmid will be induces. Since the same plasmid contains the luciferase genes, luciferase will also be produced and the bacteria will bioluminesce. This bioluminescence is directly related to the presence of the targeted hazardous chemical and constitutes the analytical signal. The genetically designed bacteria will be employed in the development of biosensor based detection systems. By positioning these bacteria in front of optical fibers highly sensitive and selective biosensors will be developed capable of monitoring the level of Superfund hazardous substances in environmental samples (groundwater and soil). The construction of the sensors will be optimized with respect to the optical design, bacteria selection, and bacteria immobilization. Factors such as response time, selectivity, and effect of the solid surface in the case of soil will be evaluated. Further evaluation will be carried out by testing the sensor response in actual Superfund samples and quantification of the contaminants using traditional extraction and spectroscopic techniques.